Structural and thermal modifications induced by the binding of phospholipids to the small antimicrobial peptide jellein-I are examined by infrared, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Raman techniques. The model membranes considered are dipalmitoyl phosphatidylcholine (DPPC), palmitoyloleoyl phosphatidylcholine (POPC), and sphingomyelin. Infrared and Raman spectra revealed that jellein-I mainly adopts a mixture of β-sheet (55%) and turn (45%) structures. In the presence of POPC, jellein-I adopts β-sheet structure, but remains the same in the presence of DPPC and sphingomyelin. TGA curves revealed that the jellein-POPC association is thermally more stable than are jellein-DPPC and jellein-sphingomyelin associations. The DSC thermograms are characterized by several broad endothermic peaks which also indicated that Jellein-POPC association absorbs more thermal energy, corresponding to a higher phase transition temperature. Raman spectra are used to analyze the high wavenumber peaks found in the range 2800-3100 cm<sup>-1</sup>. Jellein-I interacted strongly with monolayers containing POPC, leading to the rigidification of lipid acyl chains. The low wavenumber peaks below 500 cm<sup>-1</sup> representing the longitudinal acoustic modes of the acyl chains are also discussed.

Vibrational and thermal analysis of the interactions between the peptide jellein-I and model membranes

251st National Meeting (2016)

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